Chapter 10 Diagnostics of Silane Glow Discharges Using Probes and Mass Spectroscopy

Publisher Summary This chapter discusses the electric probe techniques and the mass spectroscopy of glow discharges excited in pure silane and various silane–gas mixtures. Glow discharges are used to deposit amorphous hydrogenated silicon (a-Si:H) films either by the direct plasma decomposition of silane or by reactive sputtering of a Si target using a glow discharge containing some hydrogen in the gas. The gaseous atmosphere of an operating silane glow discharge contains energetic electrons, ions, fragments, and condensation products and the various species are not in thermal equilibrium with each other. The discharge, thus, provides a rich source of reactive species. The mechanism by which the glow discharge is initiated and maintained and the voltages and electric fields that are present depend on the excitation method used on the composition and geometrical properties of the electrodes and on the gas in which the discharge is excited. The use of probes to measure plasma characteristics is a simple experimental technique, but the results may be difficult to interpret. The probe usually consists of an insulated wire having a short section of the tip exposed or it may be a plane surface in contact with the plasma. The chapter shows a simplified circuit diagram, illustrating the essential features of the technique.